Thin-film nanocomposite membranes were prepared by dip-coating poly(vinyl alcohol) (PVA) and tin oxide (SnO2) nanoparticles over a polyethersulfone membrane support. PVA was cross-linked using malic acid for stability. The membranes were characterized by Fourier transform infrared spectroscopy, field emission gun-scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, atomic force microscopy, and contact angle measurement; and nanoparticles, by dynamic light scattering and transmission electron microscopy. The membranes were subjected to filtration of synthetic dyes wastewater. The performance of the prepared membranes was compared with those of membranes without SnO2 nanoparticles. A fouling study was conducted using humic acid. The structural properties of the membranes were calculated using the extended Nernst-Planck equation.